With regard to endoscopes used in surgical operations in the related art, a technology for stereoscopically viewing a subject is known (for example, see Patent Literature 1).
In the technology disclosed in Patent Literature 1, an internal angle, which is an angle formed between intersecting optical axes of multiple image fibers disposed at a distal end of an insertion section to be inserted into a body, is adjusted by deforming the ends of the image fibers, thereby changing a stereoscopic effect of an acquired image. In the technology described in Patent Literature 1, the adjustment of the internal angle based on the deformation of the image fibers needs to be performed in a trial-and-error fashion by an observer, such as a doctor, while viewing a monitor. An appropriate stereoscopic image of a subject cannot be readily acquired.